It is known to provide vehicles with motors or engines that drive hydrostatic transmissions wherein vehicle speed and direction are controlled by the hydrostatic transmission. A typical hydrostatic transmission has an input control shaft which is pivoted in a first rotary direction to propel the vehicle forward, and which is pivoted in an opposite rotary direction for driving the vehicle in the reverse direction. The input control shaft is typically operatively connected to a swashplate in the hydrostatic pump of the transmission. The input control shaft and the swashplate have a forward drive pivot direction, an opposite reverse drive pivot direction, and a neutral position between the forward drive and reverse drive pivot directions.
Vehicles with hydrostatic transmissions include a control mechanism or linkage structure operatively connected to the input control shaft for allowing an operator of the vehicle to control the operation of the transmission. These control linkages typically include a hand lever or foot pedals engagable by the operator during vehicle travel. These linkages typically include a neutral return feature which pivots the input control shaft and the swashplate back to the neutral position when the operator releases the hand lever or foot pedal.
It is also known to provide a “neutral start mechanism” on vehicles having hydrostatic transmissions. Such neutral start mechanisms are described for example in U.S. Pat. Nos. 5,586,955 and 4,531,365. Neutral start mechanisms prevent the vehicle power source or engine from being started while the transmission is in a driving, non-neutral mode, and thereby generally prevent the vehicle from lunging forward when started. Conventional neutral start mechanisms tend to add complexity to the overall linkage structure and contribute to a relatively high overall part count for the linkage structure.
Conventional neutral start mechanisms are typically costly to manufacture and assemble, space consuming and complex. Conventional neutral start mechanisms typically utilize mechanical slides and/or rollers, all requiring various forms of adjustment and regular maintenance.
The present inventor has recognized that it would be desirable to provide the neutral return feature for a hydrostatic transmission with an improved neutral start feature which prevents the operator from starting the vehicle when the transmission is in any mode other than its neural mode. The present inventor has recognized that it would be desirable for such a neutral start feature to be relatively simple in construction, having relatively few parts, and having a relatively low cost of manufacture and assembly.